• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.486-487
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• 2000

• Journal of Magnetics
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• v.17 no.4
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• pp.245-250
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• 2012

Ferromagnetic resonance and X-ray specular reflectivity measurements were performed on $Ni_{81}Fe_{19}/Ir_{20}Mn_{80}/Co_{90}Fe_{10}$ exchange bias trilayers, which were grown using the pulsed-DC magnetron sputtering technique on Si(100)/$SiO_2$(1000 nm) substrates, to investigate the evolution of the interface roughness and exchange bias and their dependence on the NiFe layer thickness. The interface roughness values of the samples decrease with increasing NiFe thickness. The in-plane ferromagnetic resonance measurements indicate that the exchange bias field and the peak-to-peak line widths of the resonance curves are inversely proportional to the NiFe thickness. Furthermore, both the exchange bias field and the interface roughness show almost the same dependence on the NiFe layer thickness. The out-of plane angular dependent measurements indicate that the exchange bias arises predominantly from a variation of exchange anisotropy due to changes in interfacial structure. The correlation between the exchange bias and the interface roughness is discussed.

• Journal of the Optical Society of Korea
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• v.12 no.2
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• pp.112-117
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• 2008

Single-mode propagation conditions of X-ray waveguides are investigated by numerical calculations in order to understand the importance of waveguide design parameters, such as core thickness and the optical constants of waveguide materials, on the transmission and coherence properties of the waveguide. The simulation code for mode analyzing is developed based on a numerical solution of the parabolic wave equation. The initial boundary value problem is solved numerically using a finite-difference scheme based on the Crank-Nicolson scheme. The E-field intensities in a core layer are calculated at an X-ray energy of 8.0 keV for air and beryllium(Be) core waveguides with different cladding layers such as Pt, Au, W, Ni and Si to determine the dependence on waveguide materials. The highest E-field intensity radiated at the exit of the waveguide is obtained from the Pt cladded beryllium core with a thickness of 20 nm. However, the intensity from the air core waveguide with Pt cladding reaches 64% of the Be-Pt waveguide. The dependence on the core thickness, which is the major parameter used to generate a single mode in the waveguide, is investigated for the air-Pt, and Be-Pt waveguides at an X-ray energy of 8.0 keV. The mode profiles at the exit are shown for the single mode at a thickness of up to 20 nm for the air-Pt and the Be-Pt waveguides.

• Korean Journal of Biological Psychiatry
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• v.24 no.2
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• pp.68-74
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• 2017

Objectives It is well known that problem drinking is associated with alterations of brain structures and functions. Brain functions related to alcohol consumption can be determined by the resting state functional connectivity in various resting state networks (RSNs). This study aims to ascertain the alcohol effect on the structures forming predetermined RSNs by assessing their cortical thickness. Methods Twenty-six abstinent male patients with alcohol dependence and the same number of age-matched healthy control were recruited from an inpatient mental hospital and community. All participants underwent a 3T MRI scan. Averaged cortical thickness of areas constituting 7 RSNs were determined by using FreeSurfer with Yeo atlas derived from cortical parcellation estimated by intrinsic functional connectivity. Results There were significant group differences of mean cortical thicknesses (Cohen's d, corrected p) in ventral attention (1.01, < 0.01), dorsal attention (0.93, 0.01), somatomotor (0.90, 0.01), and visual (0.88, 0.02) networks. We could not find significant group differences in the default mode network. There were also significant group differences of gray matter volumes corrected by head size across the all networks. However, there were no group differences of surface area in each network. Conclusions There are differences in degree and pattern of structural recovery after abstinence across areas forming RSNs. Considering the previous observation that group differences of functional connectivity were significant only in networks related to task-positive networks such as dorsal attention and cognitive control networks, we can explain recovery pattern of cognition and emotion related to the default mode network and the mechanisms for craving and relapse associated with task-positive networks.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1489-1496
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• 2009

Amorphous indium-gallium-zinc-oxide thin-film-transistors (TFTs) were modeled successfully. Dependence of TFT characteristics on structure, thickness, and equilibrium electron-density of the active layer was studied. For mono-active-layer TFTs, a thinner active layer had higher field-effect mobility. Threshold voltage showed the smallest absolute value for the 20 nm active-layer. Subthreshold swing showed almost no dependence on active-layer thickness. For the double-active-layer case, better switching performances were obtained for TFTs with bottom active layers with higher equilibrium electron density. TFTs with thinner active layers had higher mobility. Threshold voltage shifted in the minus direction as a function of the increase in the thickness of the layer with higher equilibrium electron-density. Subthreshold swing showed almost no dependence on active-layer structure. These data will be useful in optimizing the structure, the thickness, and the doping ratio of the active layers of oxide-semiconductor TFTs.

• Proceedings of the KSRS Conference
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• v.2
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• pp.1015-1018
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• 2006

The use of passive microwave data for estimating sea-ice thickness is limited by strong dependence of emissivity on near-surface brine. However, this particular characteristic becomes a basis for an algorithm to estimate thickness of thin sea-ice if a thickness-salinity-emissivity relationship is established. This study aims at developing an algorithm to estimate sea ice thickness on the basis of this relationship. In order to establish a thickness-salinity-emissivity relationship, we have conducted multi-platform synchronous observations in the Sea of Okhotsk. We note a positive relationship between thickness and brightness temperature. From observations, we also establish an empirical relationship between salinity and emissivity, thus between thickness and brightness temperature. The derived relationship is qualitatively similar to the one based on Hoekstra and Cappillino's formulation. Our results suggest that for thin sea-ice in the winter period there is potential to develop an algorithm to estimate sea-ice thickness.

• Tribology and Lubricants
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• v.18 no.4
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• pp.255-259
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• 2002

The tribological properties of eight different liquid crystals were investigated in a concentrated point contact device and a ball-on-flat contact. For comparison, the same tests were also performed with commercial greases and the corresponding base oils. Under the fully flooded conditions studied, liquid crystals in a concentrated point contact showed lower friction than commercial greases and greater film thickness dependence on rolling speed than grease base oils or greases. Test results also showed that the film thickness and friction were little influenced by the composition of the examined liquid crystals.

• Journal of Information Display
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• v.13 no.1
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• pp.31-36
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• 2012

Ferroelectric liquid crystal parameters, spontaneous polarization, and transition temperature were studied as a function of cell thickness. These parameters were found to increase with increasing cell thickness, but an exception was observed for the transition temperature in the case of a thin cell. A simple Landau model is presented to interpret the theoretical and experimental observations. The anomalous behavior is attributed to the electroclinic effect and is explained using the Landau model.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.703-706
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• 2009

The external electrode fluorescent lamp(EEFL) has recently been applied to backlight of LCD TV as a new light source. The dependence of the electro-optic characteristics of the EEFL used in direct-lit backlights on the glass thickness was examined in detail, and the ultraviolet(UV)-light efficiency was estimated. It was found that the lamp efficiency became larger as the glass thickness decreased if other conditions were the same.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.228-233
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• 2010

The microwave permeability was measured in order to analyze the thickness dependence of loss properties in CoFeHfO thin films with varying thickness of t = 57~1368 nm. A single resonance peak (P1) at 2.95 GHz was appeared in the samples with thickness less than 405 nm, while second resonance peak (P2) at 547MHz was additionally appeared in the samples with thickness greater than 405 nm. The P2 was originated by the angle distribution of the easy axis, which was confirmed from the measured results of the change of imaginary permeability with applied magnetic field in the sample of 1368 nm thickness and low field torque curves. If the second peaks can be reduced by minimizing the angle distribution of the easy axis, the CoFeHfO thin films with thickness greater than 400 nm can be used for the compact microwave devices operated at up to 2 GHz ranges.